Topic 2: Bacteria Flashcards
Spherical
- spherical or round
- COCCUS
-found in various habitats, including soil, water and human body
Rod-shaped
- e. coli
- BACILLUS
- commonly found in soil, water, and the human intestine
- use gliding motility
- cells joined together in a smooth, unbranched filament, trichomes)
- can also grow in branching filaments (hyphae) (clump= mycelia)
Comma shaped
- curved
- VIBRIO
Spiral-shaped
- bizarre shapes, like telephone cords
- move like corkscrews, rotating clockwise or counterclockwise to go forward or back
- works well in aquatic environments, will find them
Variable
- cant quite identify as having one shape
- called pleiomorphic, multiple shapes
Why can decreasing cell size be an advantage for bacteria?
a higher surface to volume ratio means a greater rate of nutrient/waste exchange, higher metabolic rate, faster growth rate and evolution
Bacteria that are exceptions to the typical size
Thiomargarita namibiensis
Epulopiscium fishelsoni
-both can reach close to a millimeter in length
- advantage of being big, can store more things, inclusion bodies
Things in bacterial cytoplasm (11)
DNA nucleoid
Chromosome-packaging proteins
Enzymes involved in synthesis of DNA, RNA
Regulatory factors
Ribosomes
Plasmid(s)
Enzymes involved in breaking down substrates
Inclusion bodies
Gas vesicles
Magnetosomes
Cytoskeletal structures
DNA Storage
Nucleoid
- largest region in cell
- no membrane surrounds it
- house chromosomes and DNA replication machinery
-uses several mechanisms to reduce space
Inclusion Bodies
accumulations of carbon, nitrogen, sulfur or phosphorus storage compounds
- sulfur globules: store sulfur for energy
- polyhydroxybutyrate (PHB): carbon storage compound
Gas vesicles
Used for buoyancy control
Carboxysomes
location of carbon fixation reactions (using RuBisCO enzyme)
Magnetosomes
associated with direction-finding
Topoisomerase
modify structure of DNA to enable “super
coiling”
Bacterial Cytoskeleton
- keeps everything in right place
- proteins involved in cell wall synthesis (cell division):
*MreB: defines cell shape
*FtsZ: forms ring for cell division - proteins involved in moving internal items
*Par homologues: separate newly replicated chromosomes